I should think the biggest difference between subjugating human beings to the humiliation of slavery and using animals as a means to an end lies in 1) the greater quality of the experience, essentially the conceptual grasp, that every person has of such ideals as freedom, justice, and personal dignity, which animals probably lack to any degree that is really comparable to a human being (the more intelligent animals may rightly object though, if they could), and 2) God gave us dominion over animals... Just kidding... 2) Are animals that are treated as property, but cared for and fed, actually worse off then they would be in the wild? (In terms of mass farming, where animals are bred for the purpose of slaughter, I think their lives should be made as easy and comfortable as possible... at the end of the day, perhaps call it specieism, I don't think we have the same moral responsibilities towards animals as we do towards people, but we do have some).
He who loves God cannot endeavour that God should love him in return - Baruch Spinoza
